The failure to identify and treat unhealthy drug use among patients seen in mainstream primary care settings represents a missed opportunity to improve population health. Screening, brief intervention, and referral to treatment (SBIRT) programs have been promoted to address this, but recent randomized clinical trials have demonstrated lack of efficacy. It is time to go 'back to the drawing board' to examine new models of care that could effectively address unhealthy drug use in primary care settings. SBIRT studies have only tested a 'specialist' model, which shifts the responsibility for screening and interventions onto a specialized health educator who is not part of the regular primary care team. An alternative model, which integrates screening and interventions into regular primary care, using the same approaches that are effective for other common chronic health conditions, may be more effective for reducing unhealthy drug use. Innovative application of health information technology can overcome barriers to implementing a primary care-integrated approach. The tablet computer-based Substance Use Screening and Intervention Tool (SUSIT) is designed to increase delivery of substance use brief interventions by primary care providers. The SUSIT is informed by the Technology Acceptance Model, and has three elements: 1) time and workflow constraints are addressed with patient self-administered screening completed before the clinical encounter, with results presented to the primary care provider at the point of care; 2) provider knowledge is enhanced with clinical decision support (CDS),which has proven effective at changing provider behavior to effectively address other health conditions; and 3) provider activation is improved with clinical reminders at every primary care visit. The screening component of the SUSIT has already been developed. The objective here is to build the clinical decision support, and then test the full SUSIT model with 10 primary care providers. A mixed methods approach will assess its acceptability and adoption among providers and patients, and gather preliminary data on its efficacy for reducing moderate-risk drug use (defined as unhealthy use that is below the threshold of a substance use disorder). A pre-post design will ascertain the dose of substance use intervention received and changes in drug use among patients enrolled in the screening only (SO) versus SUSIT intervention period (n=75 in each period). There are 3 specific aims: Aim 1 is to develop clinical decision support that assists primary care providers in carrying out a brief intervention. Aim 2 is to assess the impact of the SUSIT on dose of substance use brief intervention received by patients, and Aim 3 is to gather preliminary evidence on the efficacy of the SUSIT approach for reducing moderate-risk drug use. The innovation of the SUSIT approach is to leverage health information technology to support efficient and effective delivery of substance use screening and interventions. The significance of this research is that it develops and tests an alternative, practice-integrated model for addressing unhealthy drug use in primary care.